IPA: /ˈhɑːrdˌhɛd/
KK: /hɑrdˌhɛd/
A person who is stubborn or difficult to persuade, or a type of fish with a hard or bony head.
Despite everyone's advice, he remained a hardhead and refused to change his mind.
Hardhead → The word is formed from "hard" (from Old English "heard", meaning firm or solid) and "head" (from Old English "heafod", meaning the upper part of the body or the leader). The term "hardhead" refers to someone who is stubborn or unyielding, metaphorically suggesting a head that is as firm as hard material.
Think of someone with a 'firm' ('hard') 'leader' ('head') who refuses to change their mind — that's why a hardhead is someone who is stubborn.